Etymologies

From new (with b as in freebie).

(American Heritage® Dictionary of the English Language, Fourth Edition)

Origin uncertain: perhaps an alteration of newie with intrusive B (compare freebie), perhaps a shortening of new boy or newbeginner. Very likely originated in Newfoundland, where the term 'new boy' is quite common, and sounds like 'newbie' when spoken. (Wiktionary)

Examples

Thus, the number one gear advice I can give to the newbie is a good book on the basics of fly fishing.

But the newbie is usually an idealistic recent law school grads who loosens his tie after a long day in court and goes out to a bar with fellow young grads who remind each other that while you win some — and get ready for the flipperoo — you lose some as well!

Being a newbie is advantageous in that you will be viewing the culture fresh, learning the local dialect as a matter of course, and will elicit all kinds of assistance from helpful folks when shopping, setting up a bank account, etc.

To deliver such a prominent franchise into the hands of a relative newbie is a great show of faith from the publisher, but you can be sure that their decision hasn't been incidental and I don't think we'll see a drop in quality.